Author
Topic: 1987 IROC-Z (Read 3725 times)

Yeah, I know this is a 1st-Gen site but I'm almost desperate! Does anyone have any experience with TPI? In addition to my '68 I also have an '87 IROC, which is almost a Camaro . A couple of times lately the car has stalled on startup with the a/c on, and the Service Engine light comes on. Trying to restart the engine results in it runs for a few seconds then dies again. I can let it sit for awhile and the ECM will reset itself and the car will run fine. I've had it on a Tech 1 at the dealership and no codes come up. It only has 64,000 miles on it and is a cherry car and optioned to death, so it's worth fixing. I know I'm sitting on a ticking Time Bomb before whatever it is that's causing this stall leaves me stranded somewhere. I'm thinking maybe the Idle Air Control valve, but I know next to nothing about TPI. The car has developed a very slight off-idle hesitation if that helps, idles high (1500 rpm) on startup, and it only does it on an extremely hot day starting the car with the engine cold and then I turn the air on (go figure! ). Any help would be greatly appreciated.

While I'm not an expert, I did install an 88 TPI in my S10. A blast to drive. I experienced a hard start hot problem for years and couldn't figure it out. It started fine cold but hot it would act a bit like you indicated.

First off clean the throttle body, IAC motor pintle, EGR. THen use some of the expensive GM fuel injection cleaner in your tank(about $20/quart, but well worth it).

This engine uses a 9th injector for cold starts. It's not controlled by the computer, it has it's own thermostat. If it is bad it will flood the engine on hot starts. There is no copmputer monitoring of this so no codes may set. The easy way to test this is to warm up the engine, shut it off, disconnect the 8 injectors. With a fuel pressure guage on the schrader valve turn the ignition on. If the fuel pressure drops it's likely the cold start injector. In 89 they went to a computer controlled cold start with the 8 injectors.

Don't be afraid of the TPI engine. Most problems are NOT computer related, but sensor related. My S10 was the funnest vehicle I ever had for every day driving. I surprised many 5.0 Mustnags

Thanks for the links, Kevin, and the super info SS. I never knew they had a 9th injector. And you've gotta love spanking them 5.0 Mustangs! Once in my '68 I set a 5.0 out 2 lights at the drag strip, was even with him when I hit 2nd, and when my girlfriend took a photo of me crossing the line he wasn't even in the picture. You gotta love it.

TY to all who responded. The prob was the IAC valve. For some reason (humidity and heat?) the car would only act up when the temp was around 95 degrees or higher, and the engine was cold. I know it sounds crazy, but it's true. It was 103 today and sure enough, the thing puked on startup. I'd bought a new IAC valve and I put it on, and problem solved! The pintle on the old IAC was coked up and maybe the heat and humidity was enough to screw up the airflow response to the computer. Damifino. I idled the car for half an hour with the a/c on and it's cured. Hope this will help someone else with TPI.